A dentist might use strong bleach or the latest teeth-brightening lights and lasers — but drugstore whiteners can take the dingy out of your grin without sucking the cash from your wallet. Here’s a shopping guide.

STRIPS
Apply them to your top and bottom front teeth; they’re coated with peroxide gel. What’s to like — or not: Strips are easy on sensitive teeth and, starting at about $30 for a two-week regimen, they’re relatively inexpensive. But they whiten only your front teeth and can be goopy and hard to position. Best if: you have sensitive teeth.

TRAYS
Fit mouthpieces filled with peroxide gel over your top and bottom teeth; wear the trays at least 30 minutes a day for about a week. What’s to like — or not: The trays whiten teeth that strips can’t reach and stay on better too. But they can feel awkward and are more likely to cause tooth sensitivity. Prices for most are $30 to $40. Best if: you want the most complete whitening.

PAINT-ON GELUse the applicator to coat your teeth with peroxide solution twice a day after brushing. With most brands, you’ll need to wait 20 to 30 minutes before you eat or drink. What’s to like — or not: The approach is easy and cheap (some pens are under $10) and allows you to target specific teeth. But the gel is easily wiped off by food or beverages — or saliva — so it doesn’t have the whitening power of trays or strips. Best if: you don’t want to spend much — and don’t expect much.

Before bleaching:•Have your teeth professionally cleaned to remove surface stains. Your dentist can alert you to potential problems — fillings or crowns, which won’t whiten, or gum disease, which would be painful.
•If you have sensitive teeth, reduce discomfort by using a toothpaste containing potassium nitrate (such as Sensodyne ProNamel) for two weeks before you bleach.